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  1. audioguru2

    0-30 Vdc Stabilized Power Supply

    If your AD711 opamp has more thn its absolute max supply voltage of 36V, it might stop working. How many volts is your positive and negative suppies without a load on the project? Why does your supply voltage drop and how many volts does it drop? It is normal for it to drop a couple of voltas...
  2. audioguru2

    need hlep on designing reciver. ASAP...

    This datasheet for the 567 tone decoder has much more information such as the limit of the resistance for the frequency-determining pot: http://www-us6.semiconductors.com/acrobat/datasheets/NE567_SE567_2.pdf A simple way to make a 555 oscillator saves a resistor:
  3. audioguru2

    need hlep on designing reciver. ASAP...

    An LM555 or uA555 can make a square wave. But its odd harmonics are pretty high. You can filter-out the harmonics with a switched-capacitor lowpass filter IC. ;D
  4. audioguru2

    C-E Amp circuit sim using spice

    Hi Guys, I've been playing with a Spice simulator program. I took an ordinary single transistor amplifier stage then fed it a signal level that is lower than would cause the transistor to saturate or be cutoff. With the emitter resistor bypassed, it had high gain but also had 40% distortion...
  5. audioguru2

    need hlep on designing reciver. ASAP...

    When an LM567 detects a tone that it is adjusted for, then its open-collector output goes low with up to 100mA current sinking ability. You don't need to turn on and off the power supply of your other circuit, you just use the open-collector output of the LM567 to gate it on and off. ;D 
  6. audioguru2

    Do people build stuff for a customer?

    Hi Patrick, Welcome to our forum. ;D Somebody here might design and build your system for a fee. Your idea might have problems: 1) To have a range beween units more than a few cm they must use radio transmitters and receivers. Transmitting a radio signal might be illegal in your country. What...
  7. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Smit, Your project's U3 and Q3 aren't working properly. Check the pins layout of Q3 and the values of R19 and R20. Q3 should turn on when the output of U3 drops 5V and more below the positive supply voltage. Test Q3 by connecting a 10k resistor from its base to ground and it should turn on...
  8. audioguru2

    Mini Metronome

    Hi Mastrila, This project? http://www.electronics-lab.com/projects/oscillators_timers/009/index.html A switch that is "ganged" with P1 is the pot with a built-in switch that turns off the project when you turn it all the way down. Use a separate on-off switch if you want. An N-channel Mosfet...
  9. audioguru2

    need hlep on designing reciver. ASAP...

    You can detect tones with an LM567 tone decoder IC. Google says that it is discontinued but only the old metal cased one. I think your selected frequencies are too close together for it.
  10. audioguru2

    need hlep on designing reciver. ASAP...

    Hi Eceto, You need a radio receiver but you don't say the frequency nor how sensitive it must be. What's the relay for? You want a voltage to come from the receiver when it detects a transmission, so why can't that voltage actvate the new transmitter directly? There are ways to activate...
  11. audioguru2

    LM386 Amp with 4 Ohm Speaker

    Hi Tubby, The datasheet shows how inefficient the LM386 is with a 4 ohm load. It can supply only a whopping (hee, hee ;D) 300mW to a 4 ohm speaker with fairly high distortion. With a 6V supply. it would get hot at only 300mW output. With a 9V supply, it would be even hotter but the max output...
  12. audioguru2

    Bass Extender

    Hi Decade, I haven't used tubes for about 40 years. It is probably best to have the best of both worlds. If they are matched then you can hope they wear the same, but if they don't then you can adjust the bias to gain more life from them but at reduced power. ;D Today my solid-state stereo amp...
  13. audioguru2

    Transistor clarification

    Hi Mr. Heckles, You should read about transistors in our Articles section. The base-emitter junction of a junction transistor is a silicon diode! A small transistor has about 0.7V across it at a few mA of collector current but it changes a little with changes in temperature and current. You...
  14. audioguru2

    Bass Extender

    Hi Ante, That's a nice looking new old amp. Its chrome plating must add something good to its sound. It has excellent output transformers in a Williamson arrangement, isn't it? I like the negative feedback around the entire power amplifier part. 415VDC! Low distortion at only 1W output...
  15. audioguru2

    Help with Sleeping-Aid plzz!!

    It wouldn't be difficult to mod it to make a coil-launcher out of it. It just needs a little more power in its coil. Then it could shoot many steel washers all over your room making a noise and the few that hit you should wake you. ;D
  16. audioguru2

    Bass Extender

    Hi Ante, I got rid of my only tube amp long ago when I couldn't keep its outputs matched. It was a kit and had horrible distortion. Today I finished fixing my speaker and it sounds just like new! 5-minutes epoxy cement is wonderful stuff. ;D
  17. audioguru2

    Help with Sleeping-Aid plzz!!

    If the gadget wakes you, you could watch its blinking LED that might make you sleep. ;D You could have it slowly attract then repel other magnets. If your brain is sensitive to magnetic waves, then what happens when you pass through the earth's magnetic field when walking, driving or flying...
  18. audioguru2

    Help with Sleeping-Aid plzz!!

    Hi Yazserz, Welcome to our forum. ;D The project says that it radiates magnetic waves of 1.2Hz and 5Hz mixed together. I don't think the waves will go far enough to do anything for anybody. I think the project will help people sleep just as well if it is turned off due to the placebo effect...
  19. audioguru2

    0-30 Vdc Stabilized Power Supply

    I think I made an error on my previous calculation which I corrected. It looks like the current-setting pot has scaling resistors such that the max current the project will try to give is much too high at 4.1A. It will be even higher if the 10k pot is actually higher than 10k. If the pot is 12k...
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Smit, Don't connect the negative lead of your meter to the output's 0V terminal, connect it to the rectifier's 0V at the negative wire of C1 like this:
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